The first technical mention of the Sabbath in the Bible is in Genesis during the creation story. God mentions resting on the seventh day, which he later specifies to be the Sabbath. Exodus 16 explains and details the concept of the Sabbath. God gives the instructions for the Sabbath to the Israelites, indicating that they may not work or cook food on that day.
In Exodus 20, the Sabbath becomes part of the 10 Commandments, written in stone. In Exodus 31, God says that the Sabbath is to be a sign between him and the Israelites for generations in the future. He further says that it is a "lasting covenant."
In the New Testament, Jesus' treatment of the Sabbath appears to break many of the Old Testament laws. He gathers food on the Sabbath in Matthew, teaches on the Sabbath and heals on the Sabbath.
After Jesus' death and resurrection, the apostle Paul later addresses the Sabbath in the books of Galatians and Romans. He talks about believers being enslaved by ceremonies and festivities, referring to the Sabbath as one of the Jewish ceremonial feasts. In Romans he admonishes believers not to condemn any other believer for keeping any particular day of the week holy.